Background: The risk of ischemic heart disease (IHD) [reduced blood flow/oxygen supply to the heart muscle], and in particular myocardial infarction (MI) [“heart attack”], is increased amongst patients with established rheumatoid arthritis (RA). Few studies have included contemporary patients with RA.

• We recently reported that the risk of IHD is not elevated before the onset of RA symptoms.

• However, when, in relation to RA diagnosis, the risk is increased is unknown.

Objective: To assess the risk of MI and other IHD events amongst patients diagnosed with RA during the last decade and within 18 months following RA symptom onset, compared to the general population, by time since RA diagnosis, year of RA diagnosis and by rheumatoid factor (RF) status.

Methods and patients: A Swedish inception cohort of RA (number = 7,469) diagnosed between 1995 and 2006 and a matched general population comparator cohort (number = 37,024), was identified and linked to national registers of morbidity and mortality from IHD. Relative risks (RRs) of MI and other IHD events were estimated using Cox regression.

Results:

During follow-up, 233 patients with RA and 701 controls developed a first MI, corresponding to an overall RR of MI of 1.6 (95% confidence interval 1.4, 1.9). Note: a risk ratio of 1.0 would indicate no difference in average risk. [Note: The RR of 1.6 indicates average risk in these RA patients was increased by 60%.]

Increased risks of MI were already detected within 1 to 4 years following RA diagnosis, as well as in:

• Patients diagnosed with RA during the last 5 years,

• In RF-negative patients [Note: RF (rheumatoid factor) is an antibody considered an indicator of RA not normally found in healthy people. It escalates so that it is detected via blood tests in 33% of patients at 3 months after diagnosis and in 75% at one year. As many as 20% of RA patients remain RF negative.]

• And for transmural as well as nontransmural MIs [a transmural MI affects the full thickness of the heart wall].